Swingline : A vertically suspended rope knotted on the lower end to provide hand grips, hung above the boat landing on an offshore platform, and used to facilitate safe personnel transfer between boat and platform and vice versa. (RP 54)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}